SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8d3cd6ae01d16e947b96fce46228ca86be7bd6e21a83b42fcd059d78371fc1e' 
  AND token = 'Ne6qfc4qzy6+8lAffkBfHkrXaB09EKIqPWK9/GnIcPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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