SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '764f343730c71684ad6486b705c13fa1a39c7a2b2bf44112829c6a51d4b35db5' 
  AND token = '+QtpOZJxRYRhItIRzMSYPsjWUYVvVzeoZCS0B+KSwQU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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