SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76beab10a2cda04d470c534fe61c8259e0ccd80da8958401fdb8be668841f7ab' 
  AND token = 'HHC7/vrRY+mjz0UNhNJ+HQyS+x21XtxTIaN003L21lI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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