SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3eb264725bae31355bf4d4f39c5a32609d9d92234d55915f788266de854ea58' 
  AND token = '1emDe2t63pCKCXvW+pyTFEbam6SKtSO+/EVXty/huZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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