SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b43ea4a23e667faf15018edcbee4709efda5ed8a746bff43e5982a0d3f05079' 
  AND token = 'C9heu7LPDfHx7dE1UdQEI0runnL85gMM3GDLWDtoCTE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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