SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3ea39383a521edccf79db376c2addf4fd900d38529102cc53b532a1582f1cbe' 
  AND token = '4QSGwW+BPq3TZj8VUcQ3J2QaLsxLKpE+SRPiiKZD3Oc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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