SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b31c780edac10e575f9b2a315c37c0b163c99aef71d6281e61d25d7324bf011' 
  AND token = '5R7g3LqZlXFW1dAeB4ervoHdMpJlRXHP9y1WDKZklEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}