SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68dfb2e15d61d48116f432c644821f80b1791499eea29b5d8302e23c96bc2aa5' 
  AND token = 'L4/+ozb5njfeB/D9YBzKdX7wZP7BJwiQQMA4pdzOzlc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00072

JSON explain

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