SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ab245034724133aecfa67c4e2848b84fe775263f0b2b61414697511f860db52' 
  AND token = 'ZlowBQPgZMZqeKErtDr9rVVHs6tpzq5+k1XQE/FCeKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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