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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa8573ff5b75ef3c64598ad445db78f549e3f9447311e663d3550f1af9b7e307' 
  AND token = 'xZ83taMKRieQO+ZFJEWVS+NPrM8MnMIqLCAjkKWzMKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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