SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '290a145676e280b977bd6aca63f42c10a84c9294a21dbb993234500768aeef5f' 
  AND token = 'diWXTrTgqRrIG0zkZEDdOq57sthJfrieHEQflGkNZcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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