SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ec9eecc21a0174de96e745a82fe0ec131778d493281660db5549d2981649d9d' 
  AND token = 'yvC50ftkSWlOXUyrHjkFjLJW6PDvr9YzRggz1B84FNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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