SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7b0f8b9644f760415f2528e6a22a61b31c84896e7eda34db919eb80de516c44' 
  AND token = 'R8aNjgntBiKOhGlcZ9wBKVfrBDCs+I/LVGSzN1LO1EE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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