SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f72318bd269aadfc360cfd589246d51e1a46015a9bcf25bba0af512cd7ab468' 
  AND token = '1PPxrQVOOb5pTZjvUoV062nljdYIig2f3i8dCFK8+YE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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