SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d4829cdb02318002906fbe021dfef2321097aeed0723ef91e3dfaa3c458f7ce' 
  AND token = 'H5L7uIAMnk9Y1yVniVBWATVx/SKYt6aLWqdlEZFtIDA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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