SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da34714f2c3aced618f7ca9f35c44fc369b35c405355f5bd9e764b43da395b5a' 
  AND token = 'W+DCm0/M6V78Qh+UJFeCXG4AqhLKBQ1DBb21TyASI8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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