SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b778881eea4c10f0981d510fb9324486170ac2d47b4dc33774e2a50fee93524f' 
  AND token = 'HuyoZjQUUSQZFHOqdafBcdpohSuSHPGOVA6GQBZoQnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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