SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '372e70e6d329be0537059e49952f4052e83096c472faa90a31052108af4175ff' 
  AND token = '9wGkVRiakcUL9dvwXloVHGsOR7mA0wMkNeMsx+FFGrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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