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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4afe64d60f13d3a7c0f9dd0c82463c9137a9888d00e4c694fed2a879843e71f3' 
  AND token = 'klmtNSNVeFhyDMTgn7yn9qAGL3bwNSXHQ4b9Nxffuaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}