SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a61ce88aebfca5a7d2d44b49a3773674195bc52299faeaf5dbb5a31dd707473' 
  AND token = 'alajESt9QoYjwkUQG5Vztm5QZ4IfYvdCLqch6Q9BjCA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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