SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b67734484843647df85591249fc02b8346bb796b37f51b0885cd1a1db930dcd7' 
  AND token = '5mErJZjKfBA2mykVsWKhjqCOWDhFhQHURTi1ugQKa5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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