SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4da64e8b8c951bfc1260c3455179959652ed0aed55af601b7a4809c352ed0d20' 
  AND token = 'XyimrhvI4HdOmEEYkoxrh03P3DflXcMngrWzBY/H07E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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