SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf516c74cf07d5116371a8179201945ee355f98ae987b4e4f1d265626d76503a' 
  AND token = 't9gTGVnsi9xZna+QMmOer/RFNlpdKTOauZKrdzDgJiY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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