SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28894bd831aaa462e7445c33f99ed517284b9574128083d14ce3eb10676113fd' 
  AND token = 'YmRjUhyJc+nAWOa3tTF6KqtPw0hrXwv2y+NDZvI3A8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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