SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00a7844b3721110164b26407238c7334f64218397fab4ec4806a138b4e35b877' 
  AND token = 'YwNARHcVAzYBUziXgeGBsai1xXHrY9jBA+9PdIYSUk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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