SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec3bc8ad855b4e04a5f64b2392b8aa541b065db89307136f00d8c696feaa7c62' 
  AND token = '7TZjESSZpgGoIeEQigPo4ZNI8MoAUXn4RMjgwIeZFGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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