SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f187345772639b85e93b15d0fe7fbcbae19d13ee2b37a08a84b15e96346b0a5d' 
  AND token = 'JMUFDfD1CBBrsOuK+OkEVCi/ZHA8xyYfYLEfi++ABFw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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