SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3d2104dad29e823d2dfffa7628dfc08349417a5df71ca86d369ffc80abed634' 
  AND token = 'kZyts768qripJTXRKF/BOXTxxlVpVYEstktpB6uhhpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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