SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79f11d6d915db5c409496cee427515bce7c74e44481ad008edd96fd21aadd199' 
  AND token = 'dmkmyVlnLv7w51m2cKN+5ZdVemmOp7MtLLCgFue1HAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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