SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7398506e599130c812ff407eeeb300194a5b98834254e62efda3070db8dfdc03' 
  AND token = 'gmOVWt1EiHD7gjKpq+VZOmRhHKZLWwQPMdn0CJj0U1I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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