SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97907b9f34f8dd39431e70c6412a49727657a46cbd25a2f4d7518bc27fa3a455' 
  AND token = '7UpJYuXca9j0+3JRapRCGEiVJT/PvFQhd0UBOaqNC90=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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