SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2f0477d2e12662566540e27070e22bd35bc78e951ac03fadea487551f24c9dd' 
  AND token = 'st2/xJh/oSCjXyMx4gEvloDW/YFwsEg7m+JEAE0gwDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00066

JSON explain

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