SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb373c97a4eb52638dab42f425b74063c685d88c263deaee9a16cd1e23976790' 
  AND token = 'fZxSUD8p/rC/zfCkVGr/s95rEhXc8Hjhd9QtAEpnqv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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