SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c255c9db294801f840b093df910128843b1a1f5513044d43741d502a8de2b4c' 
  AND token = 'ZC0HqDaRs5Lh+5iBWkXMYqdwE6Cxr2dGGLDUFT60WVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}