SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '750ceec05eee49cb315e91525823eb14ee6c3615e83563cf209f390e669284b4' 
  AND token = 'R2adooeDMSToSewQWpV8kcXx9GlVfY+Be5ZbHA9Wtac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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