SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2a48f34e1268249da52e033673995f637e44ed3e3c5f3cc6fdc7a97d6d13a50' 
  AND token = 'IWmcRwjWOhFHjMbvrBiJunmWLKEql7JKDNXn3CVdImY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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