SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2f9859d0c8328b9d100bf93cf17b7480ebf187ca076f62555b93e6f2f7a46f7' 
  AND token = 'R0H/4RB5mOtfSuRrl1cdBqjJb9+kOzzhx8Uh1wCQXb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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