SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '387ff224430b6cf82274ba98dd46c2339bc308942b6972265ed48695d524573d' 
  AND token = 'y4+ZGYirccR7rQgrZayFacbNVSIuC7jJcYFbGOFVV4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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