SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '198d55a884116fcda74e6d3026495360d329271aa64b44c11fefed7d5da35812' 
  AND token = 'lvljybWLaIHYpaEsx1pm4BkeTuwZmh8Xv2XihJhzXzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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