SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f74c8efc42c94253970b10d805a64988b2270bf0542bf09a4e9506deee53603' 
  AND token = 'LA8g5x4EGOMYrV3mnXwTGFPbYuIqdHHXMNIx3gJIyZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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