SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd844201ae18076b58dd1951ac97e24c365d465f325967b8b1bf16a763023192a' 
  AND token = 'emjKMUfBanA19KQs0mP42zwCdlzlZfdNZQeVtMygXCI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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