SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c26798e04a09dae0937f3f1417d65c2f1af37998071ac95969c1e3a085b4b676' 
  AND token = '3NkXLKo/XEgVGFy0H02IelUihkYUkkB4D0rXP43v0so=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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