SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f361e91a3e6ea47fa0a90c8025984d0aba7696807255e96dd2e5fdc7b3d7f20b' 
  AND token = 't3ORRD9SnK0H8Uz1vqtUZ0xihHRg0gTl1hh8/MJolm8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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