SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '791b3c8c5c453fcda1457ee2ba0021b09304fafeceb703b0f21bc251872021d1' 
  AND token = 'Qf2foUMdxNv3rzwc3gPw679zycN0r06mXNVOBzz5IYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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