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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec13e7eb799cec2a2065ac8dde0e4544cd7b3e4992f307a489a5a183042ad2c0' 
  AND token = 'UTnH/sr4hNPYs/0UjOXSZdWiqPrz4WGBBMKp+Zz1Buk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}