SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b989a0f6adc5796bfb49302b943cd5fdab616e74cf70714c7331e0277d995ab' 
  AND token = 'jqstDUZiPUcz66Z1tKzMngvP/5fuW7U9p3eWeYB81VI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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