SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8503d1c225d1ef94a4f2dd4498fd91528f1639a498a1e8be99dc27f30afc558' 
  AND token = '+9tzYdm2f9GkYLtQxciqV7yG3FT+Swmv0DwOrIKyaTg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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