SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfe35e371df5404f9c0e9b7c4f4baeb3a3be75c628ced4151fa510dcade25ac3' 
  AND token = 'nZPFe4JXx1SOUfmBhmnNLfJbFHiJM3lw/bCDQoLbZr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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