SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a9f510df01189a7052aae40c93aa64c234021ed65f866291994c32a54fe6b4c' 
  AND token = 'sCnAEFjwqT5J7JGlFN0sg8MGGucOZCdKXazZjBWOhvE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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