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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b36b50df649a4d86e47bae3c459d18a28228a22b18ab960a39e0b5d6f84d9eed' 
  AND token = 'LQ9lPp4lvVQ6Ibe7ZWDXQHnVr9PQtQBRTroR7Po8L1A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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