SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c876bc516d214ba78cf11a13320656f1db72248b184e45eb60f70253564703b' 
  AND token = 'vnhQHier1GDfKDixdngGgYaOeSSLygQD1n+x3+f5ttg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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