SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '505e6ba32d365be34dd878feb3a47465aa2889a4b98b0a611d81066c68c121ca' 
  AND token = 'tDWmSRIahmAXPGl3amAqKLwOwp24X9YbyjxjvAfFlao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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