SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50cd187a0bef890f596db7d65e78e46c31504cf08e51dbd1cc593cde26f19142' 
  AND token = 'Sq7AiiUxhlI06yYT3aeXP5EJg/rponFnLVvoldeOEnU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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