SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1085858650707767ba9311ec558619b262f4f1d185c4ad060ccec2a23b116b5' 
  AND token = '15rpYffVsFi16104duQdeGjR4XAlzmeibzjcN1B2Dcw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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