SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b594f434e7d36066e926bcbfc57ee9adbb6008a1db68e0abb302fe9940449164' 
  AND token = '+xqYatKBXXx+2/IFZjrsGScHp8SKdYdAw9C8W/SqwDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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