SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fcca0be731540b8cdf92d094ff226077d0dfc343a435cdee9bb2bd693251ba9' 
  AND token = 'pKUDSc+IG7KKiMx6nm0LmTFswajKdRNr/oq+0qjiD/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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