SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5d90adf244a6182480e4875355212eacc2bebacb5e89646e4949ae717863953' 
  AND token = 'PxHcIFKDJN5rBAqRDsgrwvlbfb9QkEm93AqBYqTe87E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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