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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c62ff93a74400fc614f870548ab940e8381325842d8dcdddbea07b2c5bd9f8c0' 
  AND token = 'xMD2EHx7KtMQ8HE2lIlNHAYBXZBR1WJZc3xHZeQSNjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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