SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4340df81fd74271d578ec5c867cca79c0b333c6b876aa458667fd08e92da062' 
  AND token = 'LXKogZjqhEcvL4hN6/EHRJx4whqO3Z/D82YSgtXAkKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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