SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e08c8a6ed2892c102ce8ead357219ba37af5e3048a0ec946dca2d3e2bf111ec9' 
  AND token = 'PIfCwJZbPSVwXfXUXv5pze3NUpOI7v+xSKr9Mt0eCGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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