SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e84626f59f5650ea06fa26e929562456a82cfaa759d85398e34a3397af8de191' 
  AND token = 'CchSS3nN7ud7coQh6pyQl8g94uPabBbPU42J34rs+eI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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