SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '616f256875df708d62f8461cdebcd8ef72e442b513834f183dafa12a234acddf' 
  AND token = 'zX5/a2OZwG2OvZQkOqCeZeB3k+n8v4ITdwUslYLijs4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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