SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0d35ee212897bdab648c6ccba7972faa286d5114ef32d3d3a53ec9014906fe4' 
  AND token = 'dvxRubu0WDEqM9t3xs/Cf+3EeDwMaNybMUZArgu9mkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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