SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73fefccf4ebd0310b6898247a1a1adffb5259036edaefff11e9983a0f0e18494' 
  AND token = 'Hb13nBv4v+wyfAOkHc9lfVahrMX4gUAhw9whHUJuNh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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