SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a68bdbf2de9a7c937d0b7222e4e9244d979c41476f3c44a1c996cc135f9ea45c' 
  AND token = 'ehEMKU+XPFtAV7qnSEFpUi+DgG1BELbEqQDRve7zQpM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}