SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e1c55b55f01628e310b9b7574243fb0d107624937e549616e58169bf7758229' 
  AND token = 'AM+m5A6v24w4vBUgOUatKWtpUYBUfJK/yXZbDNzK30A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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