SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'debf596361729d97642f9c4da2465457a2c3f7e57f3388ed5638f5b8a6e8224d' 
  AND token = 'rSxd2EqmjHNqgzZFahVRat6Ip2VgDfFbExP4JlqqOSM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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